The present invention relates to a drive circuit for a high-voltage alternating current driving capacitive flat matrix display panel and, more particularly, to a drive circuit for a thin-film electroluminescent matrix display panel.
The conventional drive circuit for a thin-film electroluminescent (EL) matrix display panel includes high-voltage N-ch MOS drivers performing a pull-down function, and diodes performing a pull-up function. An example of the conventional drive circuit is disclosed in Nikkei Electronics, Apr. 2, 1979, "Practical Applications of Thin-Film Electroluminescent (EL) Character Display".
In such a conventional drive circuit, the phase relationship between the write pulse and the field refresh pulse sequentially varies depending on the scanning electrodes. Also, the pre-charging voltage produces a D.C. voltage depending on whether the data side electrode is selected or not. Furthermore, the amplitudes of the write voltage and the refresh pulse are asymmetrical to each other. This fact creates deterioration in the voltage-brightness characteristics of the alternating current driving thin-film electroluminescent (EL) matrix display panel. Therefore, the conventional drive circuit can not ensure a stable operation of the thin-film electroluminescent (EL) matrix display panel for a long time.
Accordingly, an object of the present invention is to provide a novel drive circuit which ensures a stable operation of an alternating current driving capacitive type thin-film electroluminescent (EL) display panel for a long time.
Another object of the present invention is to provide a drive circuit for a thin-film electroluminescent (EL) matrix display panel, which minimizes deterioration of the voltage-brightness characteristics of the thin-film electroluminescent (EL) matrix display panel.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
To achieve the above objects, pursuant to an embodiment of the present invention, a scanning side drive circuit for a thin-film electroluminescent (EL) matrix display panel includes a P-ch MOS driver performing a pull-up function in addition to an N-ch MOS driver performing a pull-down function. The N-ch MOS driver and the P-ch MOS driver are combined with each other in a predetermined timing relationship. More specifically, the N-ch MOS driver and the P-ch MOS driver are alternately activated so that the polarity of the voltage applied to the thin-film electroluminescent (EL) matrix display panel is inverted field by field. The phase relationship between the positive and negative pulses applied to the thin-film electroluminescent (EL) display panel is fixed. Also, the amplitudes of the positive and negative pulses applied to the thin-film electroluminescent (EL) display panel are symmetrical.